Within the field of watch-making, a conventional architecture is used to make movements, which are provided with striking mechanisms, such as minute repeaters. For an embodiment of this type, the gong used is a metal wire, which may be of circular or rectilinear shape. This circular metal wire may be arranged around the movement, inside the watch frame. The gong is fixed to at least one gong-carrier, which is in turn secured to a watch plate. The gong vibration is generated by the impact, generally in proximity to the gong-carrier, of at least one hammer. This vibration is made up of several natural frequencies, the number and intensity of which, in particular in the audible domain, depend on the geometry of the gong, the securing or support conditions of the gong, shock conditions and the physical properties of the material. The vibration of the gong is also transmitted to downstream elements in the watch case via the gong-carrier, and radiated in the air.
When the striking mechanism hammer strikes the gong or gongs in a striking mode, the gong starts to vibrate with superposition of all its natural modes of vibration. The gong can thus vibrate with various modes of vibration in the audible frequency range of 100 Hz to 20 kHz. For a gold or steel gong for example having a diameter of 0.6 mm and a length close to 90 mm, a first natural mode of vibration is generally close to 100 Hz, and the density of the modes of vibration may be up to 3 kHz−1 particularly within the frequency range of 3 kHz to 10 kHz. The first modes of vibration below 1 kHz generally cannot be efficiently radiated by the watch elements. The actuation thereof thus represents a loss of acoustic energy, which is a drawback. Moreover, too great a spectral density can create a sound that is much too rich, which may thus become cacophonous, which is also a drawback of conventional striking mechanisms.
To generate a harmonious sound, it is generally necessary to control the frequency contribution of the vibration generated when the gong is struck. Optimization of the conditions of impact of the hammer on the gong is insufficient to select the desired frequency composition and thus harmonic tuning. In particular, this does not increase the purity of the sound produced.